SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '781bc1020ec28dc4644f13188da588dfbd93a3d09529e57c94f08a08fff5c6ea' 
  AND token = 'HCdMyTfxfPjfzTk2C57LzQdOsN50dnNWWGAozbNlDKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}